Associations of obesity and circulating insulin and glucose with breast cancer risk: a Mendelian randomization analysis - Shu, Xiang; Arndt, Volker; Behrens, Sabine; Brenner, Hermann; Burwinkel, Barbara; Canzian, Federico; Chang-Claude, Jenny; Hamann, Ute; Kaaks, Rudolf; Schneeweiss, Andreas (International journal of epidemiology, 2019)